Experimental analysis on the resistance of fixing nails for spine cages

Arthrodesis is one of the most common surgical treatment for the management of pathologies concerning the intervertebral discs. Special cages replace the intervertebral disc and realize the fusion between the vertebral body, often together with a fixing plate, screws, and rods. An alternative method is a cage that contains integrated screws, designed with suitable holes, it allows an easier insertion of fixing system during surgery. Mt Ortho company offers a cage equipped with two diverging locking nails in Ti6Al4V-ELI titanium alloy. These nails are placed directly inside the cage inclined by 30° with respect to the horizontal. This paper, performed in collaboration with Mt Ortho, reports the experimental tests aimed at evaluating the performance of locking nails under pull-out stresses. To evaluate the nails pull-out in a more physiological way, together to the standard condition, tests were performed on a composite layer made of wood and foam. Furthermore, the notch effects generated by the locking nails are qualitatively evaluated by photoelastic analysis, in view of a geometry able to reduce the stress concentration factor on the bone tissue, without reducing the pull-out resistance.

The IGF system in thyroid cancer: new concepts

In recent years, the activation of the insulin-like growth factor (IGF) system in cancer has emerged as a key factor for tumour progression and resistance to apoptosis. Therefore, a variety of strategies have been developed to block the type I IGF receptor (IGF-I-R), which is thought to mediate the biological effects of both IGF-I and IGF-II. However, recent data suggest that the IGF signalling system is complex and that other receptors are involved. To unravel the complexity of the IGF system in thyroid cancer, IGF-I and IGF-II production, and the expression and function of their cognate receptors were studied. Both IGFs were found to be locally produced in thyroid cancer: IGF-I by stromal cells and IGF-II by malignant thyrocytes. Values were significantly higher in malignant tissue than in normal tissue. IGF-I-Rs were overexpressed in differentiated papillary carcinomas but not in poorly differentiated or undifferentiated tumours, whereas insulin receptors (IRs) were greatly overexpressed in all tumour hystotypes, with a trend for higher values in dedifferentiated tumours. As a consequence of IR overexpression, high amounts of IR/IGF-I-R hybrids (which bind IGF-I with high affinity) were present in all thyroid cancer histotypes. Because of recent evidence that isoform A of IR (IR-A) is a physiological receptor for IGF-II in fetal life, the relative abundance of IR-A in thyroid cancer was measured. Preliminary data indicate that overexpressed IRs mainly occur as IR-A in thyroid cancer. These data indicate that both IR/IGF-I-R hybrids and IR-A play an important role in the overactivation of the IGF system in thyroid cancer and in IGF-I mitogenic signalling in these tumours. J Clin PATHOL: Mol Pathol

Intravenous versus oral initial load of propafenone for conversion of recent-onset atrial fibrillation in the emergency room: a randomized trial

BACKGROUND

Non-valvular paroxysmal atrial fibrillation is a common clinical condition associated with a high risk of thromboembolism and hemodynamic problems which increase with the duration of arrhythmia. Therefore, even if arrhythmia ceases spontaneously within 24 hours in about half of the patients, a higher early conversion rate is desirable. Propafenone either by intravenous or oral load has been shown effective in conversion to sinus rhythm.

METHODS

We consecutively randomized all emergency patients with non-valvular atrial fibrillation lasting no more than 48 hours to either intravenous or oral initial load of propafenone. They all received further oral doses if still on atrial fibrillation after the initial load. Exclusion criteria were: mean ventricular rate < 65 b/min, age > 75 years, recent acute myocardial infarction, overt heart failure, conduction defects, ventricular preexcitation, thyroid dysfunction, renal or hepatic insufficiency, pregnancy, current treatment with propafenone or other antiarrhythmic drugs, and intolerance to propafenone. Primary and secondary end-points were the conversion to sinus rhythm within 12 and 48 hours of randomization respectively.

RESULTS

Ninety-seven patients were randomized to intravenous (n = 49) or oral (n = 48) treatment. Overall, sinus rhythm restoration occurred in 83.3% of patients within 12 hours and in 98.9% at 24 hours. Recovery rate resulted significantly greater for intravenous treatment at 1 and 3 hours (p < 0.001 and p = 0.001, respectively). At 6, 12 and 24 hours no significant difference between the two groups was observed (p = 0.77, p = 0.81 and p = 0.99, respectively). No patient needed treatment suspension.

CONCLUSIONS

In patients with recent-onset non-valvular atrial fibrillation treated with propafenone within 48 hours, conversion to sinus rhythm occurred in more than 80% within 12 hours. Even if intravenous initial load appears to be slightly more rapid, the oral way is easier to administer and cheaper. The choice may depend on the specific organization of the single emergency room.

A quantitative reverse transcription and polymerase chain reaction assay for human IGF-II allows direct comparison of IGF-II mRNA levels in cancerous breast, bladder, and prostate tissues

Previously, we showed by in situ hybridization that insulin-like growth factor (IGF)-II is upregulated in approximately 50% of prostate, breast, and bladder tumours. In this study, a quantitative competitive reverse transcription and polymerase chain reaction (QC RT-PCR) assay was established and used to quantify human IGF-II mRNA levels in cells and tissues. In this QC RT-PCR assay, a competitor IGF-II RNA, prepared from a newly constructed plasmid encoding the human IGF-II sequence with a 110-bp fragment inserted, was added to RNA samples prior to RT-PCR. The human IGF-II specific QC RT-PCR assay has allowed us to readily compare the levels of IGF-II mRNA in human tissues and cultured cells. Consistent with our previous observations by in situ hybridization, IGF-II mRNA was up-regulated in 50% of cancerous breast tissues examined as compared to the matching benign tissues, and IGF-II mRNA levels were higher in bladder tumours than breast and prostate tumours. In summary, we present here quantitative data confirming that a subclass of breast cancer samples has elevated levels of IGF-II transcripts by the new competitive RT-PCR assay.

Promoter usage for insulin-like growth factor-II in cancerous and benign human breast, prostate, and bladder tissues, and confirmation of a 10th exon

Upregulation of insulin-like growth factor (IGF)-II expression has been reported for a variety of childhood and adulthood tumors. We determined IGF-II gene promoter usage in human cancerous and benign tissues by semiquantitative RT-PCR using P1-P4-specific primers. Although the human IGF-II gene structure is commonly thought to consist of nine exons and four promoters, we detected substantial utilization of a previously reported exon 4b, which is downstream of exon 4. Thus, exon 4b was intensively studied using 4b-specific primers. IGF-II gene promoter usage is highly variable in malignant and benign breast, prostate, and bladder tissues. While a majority of samples utilized P2-P4 promoters in a variety of combinations, when quantitated, P3 and P4 promoters were much more active than P2 promoter. This study not only demonstrated that IGF-II gene promoter usage is highly variable in malignant and benign tissues, but suggested that alternatively spliced exon 4b should be recognized as a 10th exon.

Insulin receptor isoform A, a newly recognized, high-affinity insulin-like growth factor II receptor in fetal and cancer cells

Insulin-like growth factor II (IGF-II) is a peptide growth factor that is homologous to both insulin-like growth factor I (IGF-I) and insulin and plays an important role in embryonic development and carcinogenesis. IGF-II is believed to mediate its cellular signaling via the transmembrane tyrosine kinase type 1 insulin-like growth factor receptor (IGF-I-R), which is also the receptor for IGF-I. Earlier studies with both cultured cells and transgenic mice, however, have suggested that in the embryo the insulin receptor (IR) may also be a receptor for IGF-II. In most cells and tissues, IR binds IGF-II with relatively low affinity. The IR is expressed in two isoforms (IR-A and IR-B) differing by 12 amino acids due to the alternative splicing of exon 11. In the present study we found that IR-A but not IR-B bound IGF-II with an affinity close to that of insulin. Moreover, IGF-II bound to IR-A with an affinity equal to that of IGF-II binding to the IGF-I-R. Activation of IR-A by insulin led primarily to metabolic effects, whereas activation of IR-A by IGF-II led primarily to mitogenic effects. These differences in the biological effects of IR-A when activated by either IGF-II or insulin were associated with differential recruitment and activation of intracellular substrates. IR-A was preferentially expressed in fetal cells such as fetal fibroblasts, muscle, liver and kidney and had a relatively increased proportion of isoform A. IR-A expression was also increased in several tumors including those of the breast and colon. These data indicate, therefore, that there are two receptors for IGF-II, both IGF-I-R and IR-A. Further, they suggest that interaction of IGF-II with IR-A may play a role both in fetal growth and cancer biology.

Insulin receptor activation by IGF-II in breast cancers: evidence for a new autocrine/paracrine mechanism

IGF-II, produced by breast cancer epithelial and stromal cells, enhances tumor growth by activating the IGF-I receptor (IGF-I-R) via autocrine and paracrine mechanisms. Previously we found that the insulin receptor (IR), which is related to the IGF-I-R, is overexpressed in breast cancer cells. Herein, we find that, in breast cancer the IR is activated by IGF-II. In eight human breast cancer cell lines studied there was high affinity IGF-II binding to the IR, with subsequent IR activation. In these lines, IGF-II had a potency up to 63% that of insulin. In contrast, in non malignant human breast cells, IGF-II was less than 1% potent as insulin. Via activation of the IR tyrosine kinase IGF-II stimulated breast cancer cell growth. Moreover, IGF-II also activated the IR in breast cancer tissue specimens; IGF-II was 10-100% as potent as insulin. The IR occurs in two isoforms generated by alternative splicing of exon 11; these isoforms are IR-A (Ex11-) and IR-B (Ex11+). IR-A was predominantly expressed in breast cancer cells and specimens and the potency of IGF-II was correlated to the expression of this isoform (P<0.0001). These data indicate, therefore, that the IR-A, which binds IGF-II with high affinity, is predominantly expressed in breast cancer cells and represents a new autocrine/paracrine loop involved in tumor biology.

Overexpression of membrane glycoprotein PC-1 in MDA-MB231 breast cancer cells is associated with inhibition of insulin receptor tyrosine kinase activity

MDA-MB231 human breast cancer cells are unresponsive to insulin and contain a glycoprotein inhibitor of insulin-stimulated insulin receptor (IR) tyrosine kinase activity. Prior studies in both fibroblasts from insulin- resistant non-insulin-dependent diabetes mellitus patients and transfected cells indicate that overexpression of membrane glycoprotein PC-1 reduces IR tyrosine kinase activity. In the present study, we measured PC-1 content and activity in MDA-MB231 and four other human breast cancer cell lines. We observed that PC-1 expression was 3- to 30-fold higher in MDA-MB231 cells when compared with the other breast cell lines. Wheat germ agglutinin extracts of MDA-MB231 cells inhibited IR tyrosine kinase activity. Treatment of these extracts with an antibody to PC-1 significantly reduced their ability to inhibit insulin-stimulated IR tyrosine kinase activity. In addition, when cell clones with different PC-1 activity were selected from MDA-MB231 cells, we found an inverse correlation (r = -0.741, P = 0.006) between the PC-1 activity and the insulin-stimulated IR autophosphorylation. A similar inverse correlation was observed in cell clones derived from the insulin-responsive breast cancer cell line MCF-7. By both immunoprecipitation and cross-linking studies we found PC-1 to be associated with IR. These studies indicate, therefore, that overexpression of PC-1 in MDA-MB231 cells may account, at least in part, for the reduced IR tyrosine kinase activity and suggest that PC-1 is a specific modulator of the IR activity in breast cancer cells.

Interleukin-1 blocks insulin and insulin-like growth factor-stimulated growth in MCF-7 human breast cancer cells by inhibiting receptor tyrosine kinase activity

Interleukins-1 (IL-1s) are known to inhibit the growth of cultured breast cancer cells. We examined the effects of IL-1 alpha and IL-1 beta on insulin and insulin-like growth factor I (IGF-I) stimulation of cell growth and found that both IL-1s inhibited anchorage-dependent and independent growth of MCF-7 breast cancer cells. In cells incubated with IL-1 beta (100 U/ml), insulin receptor (IR) protein and messenger RNA were increased by 100%, while IGF-I receptor protein and transcript were not significantly changed. These data were confirmed by binding studies. Incubation of MCF-7 cells with IL-1s led, however, to a significant inhibition of IR and IGF-I receptor autophosphorylation (-55%) and phosphotransferase activity (-65%). Also, in 3T3/ HIR rat fibroblasts, transfected with and overexpressing IR, IL-1s decreased insulin-stimulated cell growth in soft agar and IR tyrosine kinase activity. The present findings suggest that IL-1s antagonize the insulin and IGF-I mitogenic effects in MCF-7 cells by blocking the receptor tyrosine kinase activity that is crucial for the mitogenic effect of these factors.

Relationship between body surface area and arterial concentrations of bupivacaine following lumbar epidural anesthesia

BACKGROUND AND OBJECTIVES

Most prior studies have shown no relationship between body mass or body surface area (BSA) and maximum plasma concentration of local anesthetic agent (Cmax) following neural block.

METHODS

Forty-nine patients, aged 55 or older, undergoing elective total hip arthroplasty, had arterial plasma bupivacaine concentrations measured (gas chromatography) at 10-minute intervals for the first 60 minutes following lumbar epidural injection of 25 mL 0.75% bupivacaine plain. Hemodynamic stability was maintained with either low-dose epinephrine (EPI) or phenylephrine (PHE) intravenous infusions.

RESULTS

A significant relationship between arterial bupivacaine concentration and BSA was noted for both EPI and PHE groups at each observation point (P < .05). In addition, Cmax for each group was correlated to both BSA and body mass (P < .05). Arterial plasma bupivacaine concentrations were significantly higher in patients at 10, 20, 30, and 40 minutes following epidural injection in patients receiving PHE than EPI (P < .05).

CONCLUSIONS

Between 20% and 40% of the variability in the arterial concentrations of bupivacaine following lumbar epidural injection in elderly patients can be accounted for by differences in BSA.

Deliberate hypotensive epidural anesthesia for patients with normal and low cardiac output

The use of hypotensive anesthesia is contraindicated in patients with ventricular dysfunction, even though afterload reduction often improves ventricular performance. The purpose of this study was to prospectively assess systemic hemodynamic responses to deliberate hypotension with epidural anesthesia in patients with chronic left ventricular dysfunction. Hemodynamic measurements were performed in 29 patients undergoing total hip arthroplasty under deliberate hypotensive epidural anesthesia using low-dose intravenous epinephrine infusion to maintain mean arterial pressure (MAP) at 50-60 mm Hg. Intraoperative MAP decreased from 100 +/- 16 to 56 +/- 9 mm Hg by 30 min after epidural injection (P < 0.0005). Concurrently, cardiac index (CI) increased from a preanesthetic baseline value of 2.9 +/- 0.5 to 3.3 +/- 0.9 L.min-1.m-2 at 30 min (P < 0.005) after epidural injection and stroke volume index (SVI) increased from 41 +/- 8 to 50 +/- 14 mL.beat-1.m-2 30 min after epidural injection (P < 0.005). Heart rate and central venous and pulmonary artery diastolic pressures were maintained under hypotension with epidural anesthesia in all patients. During deliberate hypotension with epidural anesthesia, patients with a history of congestive heart failure or low preanesthetic CI (< or = 2.5 L.kg-1.m-2) increased their CI and SVI into the normal range. There were no significant perioperative complications in either of these groups. Hypotensive epidural anesthesia can be used successfully in patients with low cardiac output from ventricular dysfunction undergoing total hip arthroplasty.

Single versus staged epidural injections of 0.75% bupivacaine: pharmacokinetic and pharmacodynamic effects

Epidural anesthesia may be performed as a single injection or by staged doses. Thirty patients undergoing primary total hip replacement were randomly assigned to have epidural anesthesia using a single injection or a staged technique with 25 mL of 0.75% bupivacaine. Arterial plasma bupivacaine concentrations were significantly higher in the single injection group for the first 15 min but were not significantly different thereafter. Peak bupivacaine concentrations did not differ significantly between groups, but the time to achieve the peak concentration was delayed by staging injections (P = 0.001). Hemodynamic effects were similar between groups. Resolution of thoracic sensory block through T12 and duration of motor block measured by Bromage scale were both significantly longer in the staged injection group (P < 0.01). The method of epidural injection may affect resolution of neural block and the time to reach peak arterial plasma concentration of local anesthetic.

Acute exacerbation of carpal tunnel syndrome after radial artery cannulation

Acute carpal tunnel syndrome that follows radial artery cannulation has been described. To determine the incidence and predisposing factors, we prospectively studied 151 patients who had perioperative radial artery cannulation. Postoperatively 9 of the 151 patients had symptoms of carpal tunnel syndrome with positive Phalen and Tinel signs on the side on which the radial artery catheter had been inserted. Eight of 12 patients with a prior history of carpal tunnel syndrome had acute exacerbation of symptoms postoperatively. By contrast, only 1 of 139 patients with no prior history of the disorder had symptoms. Fourteen patients had multiple arterial artery punctures or perforations of the posterior wall of the radial artery. In three of these, postoperative symptoms of carpal tunnel syndrome developed but did not reach statistical significance. The only patient with postoperative acute carpal tunnel syndrome but no prior history of the syndrome had multiple arterial punctures. The use of perioperative anticoagulation, the use of wrist-extension splints, and the duration of radial artery cannulation did not influence acute exacerbation of carpal tunnel syndrome. Patients with a prior history of carpal tunnel syndrome are at increased risk of recurrent symptoms after radial artery cannulation. We found no statistically significant relationship between traumatic cannulations and the development of symptoms of carpal tunnel syndrome.

The effect of two levels of hypotension on intraoperative blood loss during total hip arthroplasty performed under lumbar epidural anesthesia

The degree of induced hypotension necessary to achieve a significant reduction in intraoperative blood loss has never been defined. Forty patients undergoing primary total hip arthroplasty during epidural anesthesia by a single surgeon were randomly assigned to have mean arterial pressure maintained at 50 +/- 5 mm Hg or 60 +/- 5 mm Hg throughout surgery. Intraoperative blood loss was 179 +/- 73 mL in the 50 mm Hg group and 263 +/- 98 mL in the 60 mm Hg group (P = 0.004). Subjectively, there was more bleeding during surgery in the 60 mm Hg group during dissection of the hip joint (P = 0.0026) and while reaming the acetabulum (P = 0.0001) and femur (P = 0.0001). No difference in transfusion requirements, postoperative hematocrit, or duration of surgery was noted. A difference in mean arterial blood pressure of 10 mm Hg from 50 to 60 mm Hg during surgery for total hip arthroplasty under epidural anesthesia has a measurable effect on intraoperative blood loss.

Pulse oximeter waveforms from the finger and toe during lumbar epidural anesthesia

BACKGROUND AND OBJECTIVES

To determine whether lumbar epidural anesthesia affects pulse oximeter signals in the upper or lower extremity, 13 ASA I patients were studied.

METHODS

Temperature and pulse oximeter probes were placed on the finger and the toe.

RESULTS

After epidural injection, the amplitude of the pulse oximeter waveform on the toe increased eight-fold but declined by 50% in the finger. The increase in amplitude of the pulse oximeter waveform in the foot preceded the temperature rise.

CONCLUSIONS

More reliable pulse oximeter signals may be obtained from the toe than the finger during lumbar epidural anesthesia. Furthermore, the increase in the pulse amplitude from the toe may aid in the early detection of successful epidural block.

The effect of two levels of hypotension on intraoperative blood loss during total hip arthroplasty performed under lumbar epidural anesthesia

The degree of induced hypotension necessary to achieve a significant reduction in intraoperative blood loss has never been defined. Forty patients undergoing primary total hip arthroplasty during epidural anesthesia by a single surgeon were randomly assigned to have mean arterial pressure maintained at 50 +/- 5 mm Hg or 60 +/- 5 mm Hg throughout surgery. Intraoperative blood loss was 179 +/- 73 mL in the 50 mm Hg group and 263 +/- 98 mL in the 60 mm Hg group (P = 0.004). Subjectively, there was more bleeding during surgery in the 60 mm Hg group during dissection of the hip joint (P = 0.0026) and while reaming the acetabulum (P = 0.0001) and femur (P = 0.0001). No difference in transfusion requirements, postoperative hematocrit, or duration of surgery was noted. A difference in mean arterial blood pressure of 10 mm Hg from 50 to 60 mm Hg during surgery for total hip arthroplasty under epidural anesthesia has a measurable effect on intraoperative blood loss.

The effect of cardiac output on intraoperative blood loss during total hip arthroplasty

BACKGROUND AND OBJECTIVES

It is not clear whether cardiac output affects intraoperative blood loss under epidural hypotensive anesthesia.

METHODS

Thirty patients undergoing primary total hip arthroplasty were randomly assigned to receive intravenous infusions of either low-dose epinephrine or phenylephrine to maintain mean arterial pressure at 50 to 60 mm Hg throughout surgery under lumbar epidural anesthesia. Patients were monitored with radial artery and thermodilution pulmonary artery catheters. Hemodynamic parameters were measured every 10 minutes during surgery, and blood loss was estimated by a blinded observer weighing sponges.

RESULTS

Mean arterial pressure was similar between groups. Cardiac output remained unchanged in patients receiving low-dose epinephrine but declined significantly in patients receiving phenylephrine (p = 0.0001). Blood loss was 228 and 236 mL in patients receiving low-dose epinephrine and phenylephrine, respectively (p = 0.86). No correlation was observed between cardiac output and blood loss at any point during surgery.

CONCLUSIONS

Cardiac output is not a factor influencing blood loss during hypotensive epidural anesthesia in elderly patients undergoing primary total hip arthroplasty.

The hemodynamic and fibrinolytic response to low dose epinephrine and phenylephrine infusions during total hip replacement under epidural anesthesia

Lower rates of deep vein thrombosis have been noted following total hip replacement under epidural anesthesia in patients receiving exogenous epinephrine throughout surgery. To determine whether this is due to enhanced fibrinolysis or to circulatory effects of epinephrine, 30 patients scheduled for primary total hip replacement under epidural anesthesia were randomly assigned to receive intravenous infusions of either low dose epinephrine or phenylephrine intraoperatively. All patients received lumbar epidural anesthesia with induced hypotension and were monitored with radial artery and pulmonary artery catheters. Patients receiving low dose epinephrine infusion had maintenance of heart rate and cardiac index whereas both heart rate and cardiac index declined significantly throughout surgery in patients receiving phenylephrine (p = 0.0001 and p = 0.0001, respectively). Tissue plasminogen activator (t-PA) activity increased significantly during surgery (p < 0.005) and declined below baseline postoperatively (p < 0.005) in both groups. Low dose epinephrine was not associated with any additional augmentation of fibrinolytic activity perioperatively. There were no significant differences in changes in D-Dimer, t-PA antigen, alpha 2-plasmin inhibitor-plasmin complexes or thrombin-antithrombin III complexes perioperatively between groups receiving low dose epinephrine or phenylephrine. The reduction in deep vein thrombosis rate with low dose epinephrine is more likely mediated by a circulatory mechanism than by augmentation of fibrinolysis.

Intraoperative adjusted-dose heparin thromboembolic prophylaxis in primary total hip arthroplasty

Intraoperative, fixed, intermittent, low-dose intravenous heparin prophylaxis has been reported to significantly reduce the incidence of thromboembolic disease from 24.3% to 8.3% after primary total hip arthroplasty (THA). This study examined the potential efficacy of adjusted-dose intraoperative heparin administration, keeping the activated clotting time at 30%-50% greater than normal. It was hypothesized that prolongation of clotting parameters in a uniform manner would further decrease the incidence of thromboembolic disease postoperatively. Sixty-one patients completed the protocol. The overall incidence of thromboembolic disease was 9.8%. Five patients had a positive postoperative venogram: four in the calf and one in the proximal deep thigh vein. One patient had a symptomatic nonfatal pulmonary embolus diagnosed by ventilation-perfusion scan. There were no complications related to heparin administration. This approach was therefore equally as effective as the fixed-dose regimen, and it further confirmed the efficacy and safety of an intraoperative heparin prophylaxis regimen. The extra efforts required to maintain a constant intraoperative level of anticoagulation did not prove advantageous over the simpler, fixed-dose regimen in reducing the incidence of thromboembolic disease after primary THA.

Intraoperative heparin thromboembolic prophylaxis in primary total hip arthroplasty. A prospective, randomized, controlled, clinical trial

Venous thromboembolic disease remains the most common and potentially fatal complication after total hip arthroplasty (THA). Proximal femoral deep vein thrombosis (DVT) is especially prone to propagate and embolize. The authors' hypothesis was that intraoperative intravenous heparin administration could reduce proximal DVT in THA. There were 286 patients who entered into a prospective, double-blind, randomized clinical trial at the authors' institution between June 1988 and May 1990. All patients had unilateral primary THA under hypotensive epidural anesthesia. The epidural catheter was placed at least 60 minutes before heparin administration. Intravenous heparin was given during surgery only. All patients received aspirin twice daily (650 mg/day) after surgery. Detection of DVT was by contrast venography on Postoperative Day 6 or 7. The study was divided into three phases. There was four groups: control (intraoperative saline), 30 minutes (1000 U heparin at beginning of surgery followed by 500 U every 30 minutes), continuous adjusted (1000 U or 1500 U initial bolus followed by continuous heparin infusion maintaining anticoagulation at 30%-50% elevation from baseline), and fixed dose (1000 U bolus before hip dislocation, and 500 U bolus before femoral canal preparation). Proximal femoral DVT was effectively reduced from 9.1% in the control group to 1.7% in the heparin groups (1.7% in 30 minute, 1.6% in continuous adjusted, 1.7% in fixed dose) (p less than 0.02). The overall DVT rate was also significantly reduced from 24.3% to 10% (p less than 0.01). No adverse effects from heparin administration were noted. Postoperative drainage, hematocrit levels on Postoperative Day 2 and at discharge, and transfusion requirements were not significantly different among the groups. The current recommended protocol is 1000 U bolus five minutes before hip dislocation, followed by 500 U bolus five minutes before femoral preparation. This, in conjunction with hypotensive epidural anesthesia and postoperative aspirin, is effective in reducing proximal DVT to less than 2% in primary THA.

Venous levels of lidocaine and bupivacaine after midtarsal ankle block

BACKGROUND

No data are available on blood levels of local anesthetics after ankle block.

METHODS

Eighteen patients received 13 ml 2% lidocaine and ten received 30 ml 0.75% bupivacaine for unilateral or bilateral midtarsal ankle blocks, respectively. Blood levels were drawn at 15, 30, 45, 60, 90, 120, and 180 minutes after injections. All patients had forefoot surgery with elastic bandages (Esmarch) applied as a tourniquet immediately above the ankle intraoperatively.

RESULTS

The mean peak level of lidocaine was 1.1 micrograms/ml, and of bupivacaine, 0.5 micrograms/ml. The mean duration of analgesia was 17 hours with 0.75% bupivacaine. Duration could not be assessed in the lidocaine group because these were ambulatory patients.

CONCLUSION

The low peak level of local anesthesia and the prolonged analgesia confirmed the safety and efficacy of midtarsal ankle block for forefoot surgery and suggest that bupivacaine may be the local anesthetic agent of choice.

Effect of i.v. low-dose adrenaline and phenylephrine infusions on plasma concentrations of bupivacaine after lumbar extradural anaesthesia in elderly patients

Thirty patients undergoing primary total hip replacement under lumbar extradural anaesthesia with 0.75% bupivacaine 25 ml were allocated randomly to receive either low-dose adrenaline or phenylephrine infusions i.v. throughout surgery. Haemodynamic measurements and arterial blood samples were obtained before the extradural injection and at 10, 20, 30, 40, 50, 60 and 90 min thereafter. Peak arterial plasma concentrations of bupivacaine were observed 10 min after extradural anaesthesia and were significantly lower in patients receiving adrenaline infusions. Cardiac output was significantly greater in patients receiving adrenaline infusions (P less than 0.01). It is postulated that the smaller circulating concentrations of bupivacaine observed in patients receiving adrenaline were caused by increased cardiac output and a greater volume of distribution than in patients receiving phenylephrine.

Haemodynamic effects and outcome analysis of hypotensive extradural anaesthesia in controlled hypertensive patients undergoing total hip arthroplasty

We have examined the safety of induced hypotension produced by extradural anaesthesia in patients with medically controlled hypertension. The haemodynamic response to induced hypotension was assessed in 38 non-hypertensive and 31 controlled hypertensive patients. All received extradural anaesthesia to T4 or above which decreased mean arterial pressure to 52 mm Hg and 55 mm Hg in normotensive and hypertensive patients, respectively. Cardiac output (thermodilution) was maintained by low dose i.v. infusions of adrenaline (1-5 micrograms min-1). No differences in the haemodynamic response to induced hypotension were observed in hypertensive patients. Data were collected also from 987 consecutive patients (353 hypertensive and 634 non-hypertensive) undergoing total hip replacement. Patients with hypertension were significantly older (68 vs 60 yr; P less than 0.001) and had greater ASA ratings (P less than 0.001). The smallest recorded systolic pressures were reduced more in patients with hypertension (57% vs 52%, respectively; P less than 0.001). The mean duration of maintained intraoperative hypotension (100 and 98 min) and estimated intraoperative blood loss (278 vs 281 ml) were similar in each group. After operation, two patients developed myocardial infarctions. None developed acute renal failure or stroke. There were three deaths; one of a patient who had hypertension. This suggests that induced hypotension with extradural anaesthesia is a safe technique for patients with medically controlled hypertension undergoing total hip arthroplasty.

[Synchronous carcinoma of the colorectum]

The incidence of synchronous carcinoma of the large intestine is rising in relation to a greater oncogenic environmental charge and increased average life expectancy. There is also a constant risk of not recognising the disease, especially in the case of small carcinoma and, to a greater extent, in patients operated during the occlusive phase. Having underlined the diagnostic value of a correct preparation of the colon prior to instrumental tests, the authors emphasise the importance of a careful intraoperative exploration of the viscera, its preliminary confinement in occluded subjects and repeated surgery in the event of doubts regarding the monolocation of the tumour. Lastly, they underline the importance of postoperative radiological and endoscopic controls since these tests mark both the successful outcome of treatment and the start of follow-up.

The effect of intravenous fixed-dose heparin during total hip arthroplasty on the incidence of deep-vein thrombosis. A randomized, double-blind trial in patients operated on with epidural anesthesia and controlled hypotension

Heparin was given in fixed doses intravenously during unilateral primary total hip-replacement operations in a prospective, double-blind trial to assess the effect on the incidence of deep-vein thrombosis. One hundred and fifty patients were randomly assigned to one of two groups before the operation. Twenty-four patients were excluded from the study, leaving 126 patients. Group I consisted of sixty-six patients who received saline solution intravenously, and Group II comprised sixty patients who received heparin. All patients had epidural anesthesia with controlled hypotension. Fixed doses of heparin were administered five minutes before the operative incision was made and every thirty minutes throughout the operation. Mean arterial pressures were maintained at between fifty and sixty millimeters of mercury in all patients. Ascending venography was done on the seventh day after the operation. The incidence of deep-vein thrombosis was 24 per cent (sixteen of sixty-six patients) in Group I and 8 per cent (five of sixty patients) in Group II; the difference is significant (p = 0.03). The intraoperative loss of blood averaged 220 +/- 79 milliliters in Group I compared with 269 +/- 109 milliliters in Group II. An average of less than one unit of blood was transfused for each patient in each group. Postoperatively, there was no difference between the groups with regard to the amount of drainage that was collected in a Hemovac device or the values for hematocrit.

Hemodynamic response to low-dose epinephrine infusion during hypotensive epidural anesthesia for total hip replacement

The hemodynamic response to reduction in blood pressure after epidural anesthesia in elderly patients is poorly defined. Therefore, hemodynamic measurements using radial artery and thermodilution pulmonary artery catheters were performed in 85 patients undergoing total hip replacement in whom blood pressure was allowed to decrease in order to minimize blood loss. Measurements were made in the lateral position prior to and after induction of epidural anesthesia to T4 or above when mean arterial pressure (MAP) had fallen to 50-55 mmHg. Four non-randomized groups of patients were identified: those requiring zero, less than 1 microgram/minute, 1-2 micrograms/minute or 2-5 micrograms/minute, respectively, of intravenous epinephrine to maintain MAP at 50-55 mmHg. In patients receiving no epinephrine, MAP, heart rate (HR), stroke volume (SV), cardiac index (CI), pulmonary artery diastolic pressure (PAD), left ventricular stroke work index (LVSWI) and systemic vascular resistance (SVR) fell significantly from baseline. Low-dose epinephrine infusions modified this response by increasing SV and CI and reducing SVR, but had little consistent effect on PAD, HR and LVSWI. Increases in SV and CI were significantly related to the dose of epinephrine administered. Low-dose intravenous epinephrine infusions preserve cardiac output during hypotensive epidural anesthesia in elderly patients.

Extradural anaesthesia in patients with previous lumbar spine surgery

We studied prospectively 1381 patients undergoing extradural anaesthesia for total hip or total knee replacement, to determine if extradural anaesthesia can be performed reliably in patients who have had previous lumbar spine surgery. Fifty-two of the 57 patients (91.2%) who had undergone lumbar spine surgery received a successful extradural anaesthetic, and 1307 of 1324 patients without previous back surgery had successful extradural anaesthesia (98.7% success) (P less than 0.0001). No late complications were observed. Causes for failure of extradural anaesthesia in patients who had previously undergone lumbar spine surgery included technical difficulty (three) and inadequate spread (two).

Complications after total hip replacement. The contralateral limb

Six patients who had a total hip replacement, as well as a trochanteric osteotomy, while they were in the lateral decubitus position had complications involving the contralateral side. The complications included transient paresthesias, massive swelling of the thigh with myonecrosis, acute renal failure secondary to myoglobinuria, and arterial insufficiency that resulted in a below-the-knee amputation. In order to elucidate the causes of the complications, the external pressure of the contralateral femoral triangle and the blood flow to the contralateral foot were monitored intraoperatively in seventeen patients. The results supported the postulate that pressure at the groin is increased intraoperatively and that this can cause vascular compromise. Other proposed causes of the complications were pre-existing vascular disease, obesity, the lateral decubitus position of the patient on the operating table, and the use of hypotensive anesthesia. We found several techniques that may minimize complications in the contralateral limb during operations on the hip.

[Detection by the immunoenzymatic test ELISA of IgM anti-Cysticercus cellulosae antibodies in the cerebrospinal fluid in neurocysticercosis]

IgM antibodies against Cysticercus cellulosae in the cerebrospinal fluid (CSF) was demonstrated by ELISA immunoenzymatic assay in neurocysticercosis. CSF samples of 41 patients were analyzed for this purpose. Diagnosis was neurocysticercosis in 26 and neurosyphilis in 5; abnormalities were not registered in the other 10 cases. Neurosyphilis samples and no-abnormalities samples were considered as control groups. ELISA IgM assay for cysticercosis was negative in all CSF samples of control groups and it was positive in 12 of the 26 CSF samples of the neurocysticercosis group (46.2%). Titers ranged from 4 till 32. Positive results were no more obtained after previous treatment of CSF samples by 2-mercaptoethanol. ELISA IgM and IgG titers were compared. IgM titers wee higher than IgG titers in two cases. Results obtained were compared to those found through complement fixation, immunofluorescence and hemagglutination tests for the diagnosis of neurocysticercosis.

Management of the recovering alcoholic who seeks cosmetic surgery

Plastic surgeons are likely to see patients who have successfully completed alcohol or drug abusers' rehabilitation programs. These patients are seeking to improve their appearance and, hence, their self-image. Unless special care is given to the recovering alcoholic, he or she is at risk of readdiction to alcohol or to drugs after surgery. Recommendations are made regarding the timing of elective operations, the use of drugs during and after the procedure, and reliance on a dependable third party to dispense drugs postoperatively.